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bcachefs: Snapshot creation, deletion
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This is the final patch in the patch series implementing snapshots.
This patch implements two new ioctls that work like creation and
deletion of directories, but fancier.

 - BCH_IOCTL_SUBVOLUME_CREATE, for creating new subvolumes and snaphots
 - BCH_IOCTL_SUBVOLUME_DESTROY, for deleting subvolumes and snapshots

Signed-off-by: Kent Overstreet <[email protected]>
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@koverstreet
koverstreet authored and Kent Overstreet committed Oct 22, 2023
1 parent a861c72 commit 42d2373
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Showing 10 changed files with 348 additions and 69 deletions.
8 changes: 0 additions & 8 deletions fs/bcachefs/dirent.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -383,14 +383,6 @@ int bch2_dirent_rename(struct btree_trans *trans,
return ret;
}

int bch2_dirent_delete_at(struct btree_trans *trans,
const struct bch_hash_info *hash_info,
struct btree_iter *iter)
{
return bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
hash_info, iter);
}

int __bch2_dirent_lookup_trans(struct btree_trans *trans,
struct btree_iter *iter,
subvol_inum dir,
Expand Down
4 changes: 0 additions & 4 deletions fs/bcachefs/dirent.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,10 +33,6 @@ int bch2_dirent_create(struct btree_trans *, subvol_inum,
const struct bch_hash_info *, u8,
const struct qstr *, u64, u64 *, int);

int bch2_dirent_delete_at(struct btree_trans *,
const struct bch_hash_info *,
struct btree_iter *);

int __bch2_dirent_read_target(struct btree_trans *, struct bkey_s_c_dirent,
u32 *, u32 *, u64 *, bool);

Expand Down
182 changes: 148 additions & 34 deletions fs/bcachefs/fs-common.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,11 @@

#include <linux/posix_acl.h>

static inline int is_subdir_for_nlink(struct bch_inode_unpacked *inode)
{
return S_ISDIR(inode->bi_mode) && !inode->bi_subvol;
}

int bch2_create_trans(struct btree_trans *trans,
subvol_inum dir,
struct bch_inode_unpacked *dir_u,
Expand All @@ -19,6 +24,7 @@ int bch2_create_trans(struct btree_trans *trans,
uid_t uid, gid_t gid, umode_t mode, dev_t rdev,
struct posix_acl *default_acl,
struct posix_acl *acl,
subvol_inum snapshot_src,
unsigned flags)
{
struct bch_fs *c = trans->c;
Expand All @@ -27,10 +33,9 @@ int bch2_create_trans(struct btree_trans *trans,
subvol_inum new_inum = dir;
u64 now = bch2_current_time(c);
u64 cpu = raw_smp_processor_id();
u64 dir_offset = 0;
u64 dir_target;
u32 snapshot;
unsigned dir_type;
unsigned dir_type = mode_to_type(mode);
int ret;

ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot);
Expand All @@ -41,37 +46,122 @@ int bch2_create_trans(struct btree_trans *trans,
if (ret)
goto err;

bch2_inode_init_late(new_inode, now, uid, gid, mode, rdev, dir_u);
if (!(flags & BCH_CREATE_SNAPSHOT)) {
/* Normal create path - allocate a new inode: */
bch2_inode_init_late(new_inode, now, uid, gid, mode, rdev, dir_u);

if (!name)
new_inode->bi_flags |= BCH_INODE_UNLINKED;
if (flags & BCH_CREATE_TMPFILE)
new_inode->bi_flags |= BCH_INODE_UNLINKED;

ret = bch2_inode_create(trans, &inode_iter, new_inode, snapshot, cpu);
if (ret)
goto err;
ret = bch2_inode_create(trans, &inode_iter, new_inode, snapshot, cpu);
if (ret)
goto err;

snapshot_src = (subvol_inum) { 0 };
} else {
/*
* Creating a snapshot - we're not allocating a new inode, but
* we do have to lookup the root inode of the subvolume we're
* snapshotting and update it (in the new snapshot):
*/

if (!snapshot_src.inum) {
/* Inode wasn't specified, just snapshot: */
struct btree_iter subvol_iter;
struct bkey_s_c k;

bch2_trans_iter_init(trans, &subvol_iter, BTREE_ID_subvolumes,
POS(0, snapshot_src.subvol), 0);
k = bch2_btree_iter_peek_slot(&subvol_iter);

ret = bkey_err(k);
if (!ret && k.k->type != KEY_TYPE_subvolume) {
bch_err(c, "subvolume %u not found",
snapshot_src.subvol);
ret = -ENOENT;
}

if (!ret)
snapshot_src.inum = le64_to_cpu(bkey_s_c_to_subvolume(k).v->inode);
bch2_trans_iter_exit(trans, &subvol_iter);

if (ret)
goto err;
}

ret = bch2_inode_peek(trans, &inode_iter, new_inode, snapshot_src,
BTREE_ITER_INTENT);
if (ret)
goto err;

if (new_inode->bi_subvol != snapshot_src.subvol) {
/* Not a subvolume root: */
ret = -EINVAL;
goto err;
}

/*
* If we're not root, we have to own the subvolume being
* snapshotted:
*/
if (uid && new_inode->bi_uid != uid) {
ret = -EPERM;
goto err;
}

flags |= BCH_CREATE_SUBVOL;
}

new_inum.inum = new_inode->bi_inum;
dir_target = new_inode->bi_inum;
dir_type = mode_to_type(new_inode->bi_mode);

if (default_acl) {
ret = bch2_set_acl_trans(trans, new_inum, new_inode,
default_acl, ACL_TYPE_DEFAULT);
if (flags & BCH_CREATE_SUBVOL) {
u32 new_subvol, dir_snapshot;

ret = bch2_subvolume_create(trans, new_inode->bi_inum,
snapshot_src.subvol,
&new_subvol, &snapshot,
(flags & BCH_CREATE_SNAPSHOT_RO) != 0);
if (ret)
goto err;
}

if (acl) {
ret = bch2_set_acl_trans(trans, new_inum, new_inode,
acl, ACL_TYPE_ACCESS);
new_inode->bi_parent_subvol = dir.subvol;
new_inode->bi_subvol = new_subvol;
new_inum.subvol = new_subvol;
dir_target = new_subvol;
dir_type = DT_SUBVOL;

ret = bch2_subvolume_get_snapshot(trans, dir.subvol, &dir_snapshot);
if (ret)
goto err;

bch2_btree_iter_set_snapshot(&dir_iter, dir_snapshot);
ret = bch2_btree_iter_traverse(&dir_iter);
if (ret)
goto err;
}

if (name) {
if (!(flags & BCH_CREATE_SNAPSHOT)) {
if (default_acl) {
ret = bch2_set_acl_trans(trans, new_inum, new_inode,
default_acl, ACL_TYPE_DEFAULT);
if (ret)
goto err;
}

if (acl) {
ret = bch2_set_acl_trans(trans, new_inum, new_inode,
acl, ACL_TYPE_ACCESS);
if (ret)
goto err;
}
}

if (!(flags & BCH_CREATE_TMPFILE)) {
struct bch_hash_info dir_hash = bch2_hash_info_init(c, dir_u);
u64 dir_offset;

if (S_ISDIR(new_inode->bi_mode))
if (is_subdir_for_nlink(new_inode))
dir_u->bi_nlink++;
dir_u->bi_mtime = dir_u->bi_ctime = now;

Expand All @@ -87,11 +177,11 @@ int bch2_create_trans(struct btree_trans *trans,
BCH_HASH_SET_MUST_CREATE);
if (ret)
goto err;
}

if (c->sb.version >= bcachefs_metadata_version_inode_backpointers) {
new_inode->bi_dir = dir_u->bi_inum;
new_inode->bi_dir_offset = dir_offset;
if (c->sb.version >= bcachefs_metadata_version_inode_backpointers) {
new_inode->bi_dir = dir_u->bi_inum;
new_inode->bi_dir_offset = dir_offset;
}
}

inode_iter.flags &= ~BTREE_ITER_ALL_SNAPSHOTS;
Expand Down Expand Up @@ -160,7 +250,8 @@ int bch2_unlink_trans(struct btree_trans *trans,
subvol_inum dir,
struct bch_inode_unpacked *dir_u,
struct bch_inode_unpacked *inode_u,
const struct qstr *name)
const struct qstr *name,
int deleting_snapshot)
{
struct bch_fs *c = trans->c;
struct btree_iter dir_iter = { NULL };
Expand All @@ -169,6 +260,7 @@ int bch2_unlink_trans(struct btree_trans *trans,
struct bch_hash_info dir_hash;
subvol_inum inum;
u64 now = bch2_current_time(c);
struct bkey_s_c k;
int ret;

ret = bch2_inode_peek(trans, &dir_iter, dir_u, dir, BTREE_ITER_INTENT);
Expand All @@ -187,29 +279,51 @@ int bch2_unlink_trans(struct btree_trans *trans,
if (ret)
goto err;

if (inode_u->bi_dir == dirent_iter.pos.inode &&
inode_u->bi_dir_offset == dirent_iter.pos.offset) {
inode_u->bi_dir = 0;
inode_u->bi_dir_offset = 0;
if (deleting_snapshot == 1 && !inode_u->bi_subvol) {
ret = -ENOENT;
goto err;
}

if (S_ISDIR(inode_u->bi_mode)) {
if (deleting_snapshot <= 0 && S_ISDIR(inode_u->bi_mode)) {
ret = bch2_empty_dir_trans(trans, inum);
if (ret)
goto err;
}

if (dir.subvol != inum.subvol) {
ret = bch2_subvolume_delete(trans, inum.subvol, false);
if (inode_u->bi_subvol) {
ret = bch2_subvolume_delete(trans, inode_u->bi_subvol,
deleting_snapshot);
if (ret)
goto err;

k = bch2_btree_iter_peek_slot(&dirent_iter);
ret = bkey_err(k);
if (ret)
goto err;

/*
* If we're deleting a subvolume, we need to really delete the
* dirent, not just emit a whiteout in the current snapshot:
*/
bch2_btree_iter_set_snapshot(&dirent_iter, k.k->p.snapshot);
ret = bch2_btree_iter_traverse(&dirent_iter);
if (ret)
goto err;
}

if (inode_u->bi_dir == dirent_iter.pos.inode &&
inode_u->bi_dir_offset == dirent_iter.pos.offset) {
inode_u->bi_dir = 0;
inode_u->bi_dir_offset = 0;
}

dir_u->bi_mtime = dir_u->bi_ctime = inode_u->bi_ctime = now;
dir_u->bi_nlink -= S_ISDIR(inode_u->bi_mode);
dir_u->bi_nlink -= is_subdir_for_nlink(inode_u);
bch2_inode_nlink_dec(inode_u);

ret = bch2_dirent_delete_at(trans, &dir_hash, &dirent_iter) ?:
ret = bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
&dir_hash, &dirent_iter,
BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
bch2_inode_write(trans, &dir_iter, dir_u) ?:
bch2_inode_write(trans, &inode_iter, inode_u);
err:
Expand Down Expand Up @@ -348,12 +462,12 @@ int bch2_rename_trans(struct btree_trans *trans,
goto err;
}

if (S_ISDIR(src_inode_u->bi_mode)) {
if (is_subdir_for_nlink(src_inode_u)) {
src_dir_u->bi_nlink--;
dst_dir_u->bi_nlink++;
}

if (dst_inum.inum && S_ISDIR(dst_inode_u->bi_mode)) {
if (dst_inum.inum && is_subdir_for_nlink(dst_inode_u)) {
dst_dir_u->bi_nlink--;
src_dir_u->bi_nlink += mode == BCH_RENAME_EXCHANGE;
}
Expand Down
7 changes: 5 additions & 2 deletions fs/bcachefs/fs-common.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,9 @@
struct posix_acl;

#define BCH_CREATE_TMPFILE (1U << 0)
#define BCH_CREATE_SUBVOL (1U << 1)
#define BCH_CREATE_SNAPSHOT (1U << 2)
#define BCH_CREATE_SNAPSHOT_RO (1U << 3)

int bch2_create_trans(struct btree_trans *, subvol_inum,
struct bch_inode_unpacked *,
Expand All @@ -13,7 +16,7 @@ int bch2_create_trans(struct btree_trans *, subvol_inum,
uid_t, gid_t, umode_t, dev_t,
struct posix_acl *,
struct posix_acl *,
unsigned);
subvol_inum, unsigned);

int bch2_link_trans(struct btree_trans *,
subvol_inum, struct bch_inode_unpacked *,
Expand All @@ -23,7 +26,7 @@ int bch2_link_trans(struct btree_trans *,
int bch2_unlink_trans(struct btree_trans *, subvol_inum,
struct bch_inode_unpacked *,
struct bch_inode_unpacked *,
const struct qstr *);
const struct qstr *, int);

int bch2_rename_trans(struct btree_trans *,
subvol_inum, struct bch_inode_unpacked *,
Expand Down
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